Method for operating a driver assistance system to support a driver during a skidding process and motor vehicle

Abstract

Method for operating a driver assistance system (13) for supporting a driver of a motor vehicle (1) during a skidding process, wherein, upon fulfillment of at least one of at least one skidding criterion indicating a skidding process, at least one support measure is implemented that issues a support instruction to the driver and / or includes a driving intervention, characterized in that radar data describing the environment of the motor vehicle (1) are recorded by means of at least one radar sensor (2) of the motor vehicle (1) and evaluated with respect to static objects (26, 27), wherein, for the detection of a skidding process by the skidding criterion, the dynamics of at least one static object (26, 27) relative to the motor vehicle (1) are evaluated in their temporal course,wherein at least one of the at least one skid criterion comprises a comparison of a motion pattern of at least one static reference object with respect to the motor vehicle (1) with at least one reference pattern describing a skid state.

Description

[0001] The invention relates to a method for operating a driver assistance system to support a driver of a motor vehicle during a skidding process, wherein, upon fulfillment of at least one of at least one skidding criterion indicating a skidding process, at least one support measure is implemented that issues a support warning to the driver and / or includes a driving intervention. The invention also relates to a motor vehicle.

[0002] Skidding poses a significant danger to both the skidding vehicle and other vehicles, representing a critical driving situation. While chassis control systems have been proposed to help stabilize a vehicle in a skid, these systems are not always able to effectively halt a skid, especially when the physical limits of the current driving situation are reached. A crucial factor is also the driver, who may not always be familiar with or intuitively understand the correct steering response during a skid.

[0003] Therefore, driver assistance systems have already been proposed to support a driver during a skidding process, which aim to indicate to the driver a sensible direction in which he can steer in order to stabilize the vehicle, based on an assessment of the current driving dynamics of the vehicle.

[0004] For example, DE 10 2009 035 634 A1 proposes a method for assisting a driver of a motor vehicle during a skid, in which a steering direction that stabilizes the vehicle is determined from parameters describing the vehicle's driving dynamics and defined by a chassis control system, and the driver's attention, in particular the driver's gaze, is directed to the steering direction by at least one further vehicle system. It can be provided that, on the one hand, the steering direction desired by the driver, defined by the steering angle of the vehicle at the onset of the skid, is used as the steering direction that stabilizes the vehicle; on the other hand, the steering direction that stabilizes the vehicle can also be calculated by a control unit as an optimally stabilizing steering direction.The system evaluates the vehicle's skidding state, as defined by its driving dynamics parameters, and mathematically determines the direction of travel that the driver should steer most effectively to correct the skidding. Various visual aids can be used to guide the driver's gaze.

[0005] DE 103 54 662 A1 relates to a method for assisting the driver in extreme driving dynamics situations by applying a steering torque. A torque in a direction in which the vehicle stabilizes is to be applied to the steering wheel to indicate to the driver in which direction to steer in order to stabilize the vehicle as quickly as possible after skidding or oversteering. This steering torque is maintained until the actual yaw rate decreases. The patent therefore proposes providing a haptic indication of a stabilizing steering direction.

[0006] A similar method is disclosed in DE 101 41 425 A1, in which a driving-condition-dependent additive additional torque is to be generated during a skidding process, which additional torque is to provide haptic feedback in which direction the steering wheel and thus the steerable wheels are to be steered in order to regain or increase driving stability. There, too, the driver is thus given haptic feedback in which direction the steering wheel is to be moved.

[0007] These established methods utilize data describing the vehicle's dynamics, such as sideslip angle, yaw rate, and the like, to detect a skid and / or generate a recommendation or indication for the driver regarding steering direction. The primary goal is to regain vehicle stability during a skid. A disadvantage of these methods is that the vehicle's surroundings are not considered, either in determining whether a skid is occurring or in the subsequent support measures. This leads to a risk of false detections and can result in critical situations if the stabilization strategy is selected without considering the surroundings.

[0008] DE 10 2006 036 921 A1 relates to a method for stabilizing a motor vehicle and a vehicle dynamics control system. Image data is acquired using an optical sensor, and the lateral velocity and / or yaw angle changes of the motor vehicle are to be determined by evaluating this data in order to assess the vehicle's driving condition. The method essentially utilizes the so-called "optical flow." The data is processed in an evaluation unit and transmitted to a control unit, which uses the data to assess the vehicle's driving condition. For example, instability can be detected. Determining the distance to the vehicle is considered advantageous, for which optical sensors with three-dimensional imaging capabilities are preferably used, such as a stereo camera or a PMD sensor. However, this additional information can also be obtained from a radar sensor.

[0009] DE 102 52 323 A1 discloses a method for determining the self-motion of a vehicle. At least two data sets from a sensor moving with the vehicle are evaluated to obtain relative velocity and relative position data relative to the vehicle at a given time. These relative motion parameters are then used to determine the vehicle's rotational velocity and / or at least one component of its orbital velocity based on a model relationship. Specifically, the basic idea is that the self-motion of a vehicle relative to stationary objects can also be determined by analyzing the relative positions and movements of the stationary objects relative to the vehicle at a given time. The sensor can be a radar sensor.Using the model relationships, a relationship can be established between the relative positions, the relative velocities, and the self-motion.

[0010] DE 10 2014 011 121 A1 relates to a motor vehicle with a collision protection system for at least one door of the motor vehicle and at least one environmental sensor that detects sensor data of an opening area in which the door moves when opened, wherein the collision protection system has at least one control unit that is designed to evaluate the sensor data with regard to objects that pose a collision risk and, in the event of a detected collision risk, to carry out at least one measure that informs an occupant of the motor vehicle and / or avoids the collision and / or mitigates the consequences of the collision. The environmental sensor for monitoring the opening area is a radar sensor with a radar transceiver implemented by a semiconductor chip, in particular a CMOS chip.

[0011] DE 10 2010 006 214 A1 discloses an emergency braking assistant for automatically braking a vehicle to avoid or mitigate the consequences of a collision with a detected object, wherein, at a determined intervention time, a braking system of the vehicle is automatically controlled in such a way that a collision with the detected object can be avoided or at least the consequences of the collision can be mitigated. The intervention time can be determined depending on the end time of a determined driver reaction time and the determined last possible braking time.

[0012] The invention is therefore based on the objective of enabling more reliable detection of skidding processes and, in particular, improved support for the driver during skidding processes.

[0013] To solve this problem, a method of the type mentioned at the outset provides that radar data describing the environment of the motor vehicle are recorded by means of at least one radar sensor of the motor vehicle and evaluated with regard to static objects, wherein, for the detection of a skidding process by means of the skidding criterion, the dynamics of at least one static object relative to the motor vehicle are evaluated in its temporal course, wherein at least one of the at least one skidding criterion comprises a comparison of a movement pattern of at least one static reference object with regard to the motor vehicle with at least one reference pattern describing a skidding state.

[0014] The invention thus proposes to improve the detection of skidding by also taking into account highly accurate radar data of the vehicle's surroundings, from which the presence of static objects and their relative dynamic properties can be derived. This is because it has been shown that typical correlations exist between dynamic parameters recorded within the vehicle itself and typical movement patterns of static objects relative to the vehicle, which allow for extremely reliable detection of a skidding event. Radar sensors have been used in motor vehicles for some time, for example, in connection with longitudinal driver assistance systems that respond to a vehicle ahead.Modern, high-precision radar sensors, however, allow for the reliable and highly accurate detection of static and dynamic objects in the vicinity of the vehicle, for which suitable classification algorithms have already been proposed. In other words, a skidding event is detected based on the relative movement and orientation of the vehicle to its surroundings, such as a guardrail.

[0015] The invention makes particular use of the now available high-precision semiconductor-based radar sensors, which also provide the suitable data for the reliable detection of skidding processes described here.

[0016] The realization of semiconductor-based radar components proved difficult for a long time due to the need for expensive specialty semiconductors, particularly GaAs. Smaller radar sensors were proposed, whose entire radar front end was implemented on a single chip using SiGe technology, before CMOS technology became available. Such solutions are the result of extending CMOS technology to high-frequency applications, often referred to as RF-CMOS. A CMOS radar chip of this type is extremely compact and does not require expensive specialty semiconductors, thus offering significant advantages over other semiconductor technologies, especially in manufacturing. An exemplary implementation of a 77 GHz radar transceiver as a CMOS chip is described in the article by Jri Lee et al., "A Fully Integrated 77-GHz FMCW Radar Transceiver in 65-nm CMOS Technology," IEEE Journal of Solid State Circuits 45 (2010), pp. 2746-2755.

[0017] Furthermore, the proposal to integrate the chip and antenna into a single package enables the development of an extremely cost-effective, small radar sensor that significantly improves space efficiency and, due to short signal paths, exhibits a very low signal-to-noise ratio. This sensor is also suitable for high frequencies and larger, variable frequency bandwidths. Therefore, such compact radar sensors can be used for short-range applications, for example, in the range of 30 cm to 10 m.

[0018] It has also been proposed to integrate such a CMOS transceiver chip and / or a package containing a CMOS transceiver chip and antenna onto a common circuit board with a digital signal processor (DSP), or to integrate the functions of the DSP directly into the CMOS transceiver chip. Similar integration is possible for control functions.

[0019] Accordingly, it is also preferred within the scope of the present invention if a radar sensor with a semiconductor chip, in particular a CMOS chip, implementing at least one radar transceiver is used. It is particularly advantageous if the semiconductor chip also incorporates a digital signal processing component of the radar sensor and / or a control unit of the radar sensor, and / or if the semiconductor chip and an antenna arrangement of the radar sensor are implemented as a single package. In this way, a compact radar sensor with short signal paths and a high signal-to-noise ratio can be realized. Such a highly integrated radar sensor also offers the possibility of special operating modes that allow the acquisition of the high-resolution radar data advantageously used here.

[0020] A further advantageous embodiment of the present invention provides that, particularly when the radar sensor is designed using CMOS technology, the radar sensor is operated with a frequency bandwidth of at least 2 GHz, preferably at least 4 GHz, and / or in a frequency range of 77 to 81 GHz. High signal bandwidths, preferably of 4 GHz, allow for excellent object discrimination, enabling even better differentiation and classification of static objects in the vicinity of the vehicle.

[0021] A particularly preferred embodiment of the present invention further provides for the use of several radar sensors covering the vehicle's surroundings in a 360° radius. This allows for the most complete possible detection of static and dynamic objects around the vehicle. This also provides an improved basis for assessing skidding. For example, eight radar sensors can be used, three of which are concealed in the front and three in the rear bumper of the vehicle. Two additional radar sensors can be provided laterally, particularly near the doors. The radar sensors generally preferably have a wide detection angle, for example, an azimuth angle greater than 140°, and particularly 150°.With a suitable design of the antenna arrangement of the radar sensor, for example with a successive arrangement of antenna elements in two mutually perpendicular directions, an angle measurement in the elevation can also be made possible, whereby, for example, an opening angle greater than 50°, for example of 60° or 70°, may be given.

[0022] As previously mentioned, basic algorithms for classifying objects during radar data analysis are already known, for example, at the coarse level of classifying an object as static or dynamic, but also with regard to precise classification. Particularly when using radar sensors in semiconductor technology, classifiers are known that can identify specific objects, such as curbs, guardrails, roadside structures, signs, plants (especially trees), or even the transition from the road surface of the currently traveled road to another substrate, in order to achieve a highly accurate determination of the road's path. In this process, the reflective properties of the respective objects / structures can also be taken into account.Of course, it is also possible to track previously detected and classified objects in the radar data, particularly to validate certain characteristics, such as classifying an object as static (i.e., stationary) when its speed is equal to and opposite to that of the vehicle. If this suddenly changes, it could indicate that the vehicle is skidding.

[0023] One of the insights gained from the present invention is that, starting from a stationary target such as a guardrail, the relative movements and trajectories of the ego-vehicle can be evaluated without difficulty. The temporal changes in the contour and orientation of static objects relative to the ego-vehicle can provide insights not only into the driving maneuvers performed by the ego-vehicle, but also into its general driving dynamics. From the perspective of the ego-vehicle, the radar sensors detect a change in the position of the static objects when the ego-vehicle is moving, even though the static objects are stationary in the world coordinate system.This change corresponds exactly to the change in position of the vehicle itself, whereby during skidding the relative trajectory no longer corresponds to a typical driving trajectory of the vehicle, so that corresponding conclusions can be drawn here in the skidding criterion.

[0024] A convenient embodiment of the present invention, designed to further increase the reliability of skid detection, involves evaluating multiple static objects within a single skid criterion and / or across different skid criteria. Ultimately, results for different static objects can then be correlated to create a broad database that enhances the overall reliability of the assessment. Alternatively or additionally, it can be provided that static objects describing the roadway of a road traveled by the motor vehicle are used. For radar sensors, roadside structures represent a static and extended object; examples include guardrails, curbs, houses, trees, and the like.If the vehicle starts to skid, the critical traffic situation can be recognized using the static environmental data detected by radar at the edge of the roadway, for example by tracking the reflection points over time.

[0025] One possible approach to the concrete design of skid detection criteria that utilize radar data involves comparing at least one of the skid detection criteria with a dynamic parameter of the vehicle, determined by measurement on the vehicle and describing its driving dynamics, in particular its speed and / or direction of travel, with a corresponding motion parameter of the dynamics of at least one static object. For example, a useful feature for radar-based detection of a skid is that the vehicle's own speed, as detected, does not correspond in magnitude to the detected speed of static targets in the vicinity. Thus, deviations in the speed values ​​from the radar measurement and other detection methods, for example against a threshold value, can be evaluated.Another useful consideration within the framework of a skid test is when a constant relative motion to the stationary object is detected, but this motion is oriented differently than the currently set direction of travel of the vehicle itself, which is used as a dynamic parameter. Naturally, such considerations can also be made with regard to other dynamic parameters of the vehicle, for example, using the sideslip angle and / or the yaw rate as dynamic parameters.

[0026] The invention provides that at least one of the at least one skid criterion comprises a comparison of a movement pattern of at least one static reference object relative to the motor vehicle with at least one reference pattern describing a skid state. As already mentioned, in one's own motor vehicle, a change in position and orientation of static objects in the vicinity of the motor vehicle is observed due to the vehicle's own movement, even though these objects are fixed in the world coordinate system. For different types of skid processes, certain characteristics of the temporal progression of the relative movement emerge, which can be described by reference patterns. In other words, typical reference patterns describing skid profiles can be stored to enable the detection and / or plausibility check of skid processes.The currently recorded movement patterns, which result from the temporal progression of the radar data relating to static objects, can then be compared with these reference patterns in the vehicle coordinate system in order to detect a skidding process.

[0027] Specifically, this could involve, for example, the reference pattern containing at least one temporal pattern of a comparison parameter describing the relative motion, for which a corresponding temporal pattern of a motion parameter can be determined from the radar data. However, correlations between such pattern patterns and / or temporal profiles of other quantities, such as the aforementioned dynamic parameters of the vehicle, can also be stored as reference patterns and their existence verified against the actually measured data. The degree of agreement can be described, for example, by a correlation value, which can be compared to a threshold value within the framework of the skid criterion. Various methods for determining a correlation between (possibly parts of) reference patterns and motion patterns are already known for other applications.

[0028] In this context, it is also advisable to use at least one boundary building object and / or an object indicating the lane boundary of a road used by the motor vehicle as a reference object. Such objects represent stationary, fundamentally existing, extensive, and easily classifiable targets, thus allowing for a straightforward implementation of the corresponding skidding criterion.

[0029] Since various types of skidding can occur in different driving situations, a preferred embodiment of the present invention provides for reducing the number of reference patterns used for comparison. This can be achieved by selecting the at least one reference pattern used for comparison from a database of reference patterns, based on at least one dynamic parameter of the vehicle determined by measurement on the vehicle and / or scaled by this parameter. In other words, this means that only reference patterns can be used, or reference patterns can be adapted, so that they are possible or can occur in the current driving situation of the vehicle. In this way, the comparison effort and thus the computational effort are significantly reduced by making a suitable preselection / pre-parameterization.

[0030] By successfully comparing a spin-out criterion with a specific reference pattern, the nature of the spin-out process is also characterized. In a particularly advantageous embodiment of the present invention, this characterization is further utilized to support the driver, specifically in the design of the support measure. A particularly preferred embodiment of the present invention provides that, upon successful comparison with a specific reference pattern, the support measure is selected and / or adapted based on that specific reference pattern.In other words, characterizing the skidding process allows for a decision on how the driver should actually be supported, for example, which actuators should be activated to regain vehicle stability. Ultimately, a mapping of specific skidding patterns, i.e., reference patterns, with corresponding counter-steering profiles is proposed to automatically select specific support measures. The implementation of such a database with these mappings can be vehicle-specific.

[0031] In particular, it can be provided that the reference patterns are assigned support data sets containing support patterns, whereby a support measure is carried out based on the support data set assigned to the specific reference pattern. As explained, these support patterns are, in particular, counter-steering patterns that are tailored to the specific type of skidding process, but can, of course, be further specified or adapted by additional driving situation parameters describing the current driving situation. Such training for the use of support patterns is particularly useful when the vehicle is to contribute, at least semi-automatically, to stabilizing the vehicle through driving interventions.

[0032] Within the scope of the present invention, it is particularly preferred if the support measure is determined and / or adapted depending on the radar data, in particular on static and dynamic objects identified in the radar data. Considering the radar data (and optionally additional environmental data describing the vehicle's surroundings) makes it particularly advantageous to evaluate stabilization strategies implemented by the support measures with regard to static and dynamic objects in the vehicle's environment and, if necessary, to utilize other driving stabilization strategies and thus support measures that lead to less critical situations for the vehicle itself and / or other road users.In other words, when selecting an optimal stabilization strategy, such as an optimal direction of travel and / or the timing of assistance, the criticality value describing the criticality of the driving situation is also kept as low as possible. This is only possible if an environmental description is taken into account, which is proposed at least via radar data in this embodiment of the present invention.

[0033] With particular advantage in combination with the consideration of radar data in determining and / or adapting a support measure, a further embodiment of the present invention can provide that, taking the radar data into account, a collision criterion indicating an unavoidable collision is checked when at least one of the at least one skidding criterion is fulfilled, and if the collision criterion is fulfilled, the support measures for mitigating the consequences of the collision are implemented. In this case, it is therefore ultimately possible to combine the driver assistance system for supporting the driver during a skidding process with a safety system for mitigating the consequences of an unavoidable collision, thus providing a further increase in safety.Whenever a skid occurs, the system checks, using methods generally known from such safety systems, whether a collision is unavoidable. This involves considering radar data describing dynamic and static objects in the vehicle's vicinity to fully assess the current driving situation. The appropriate support measure can then be selected to mitigate the consequences of a collision, for example, by pre-conditioning passive safety systems and / or by selecting a suitable vehicle guidance / stabilization strategy to ensure a favorable point of impact between the vehicle and the object, as is generally known from such safety systems.In particular, the vehicle can be counter-steered or its orientation adjusted to minimize the severity of the collision. As a support measure, it is especially possible to control the individual wheels of the vehicle, for example, by repeatedly braking and steering, to achieve a suitable point of impact. Ultimately, the radar data is used to predictively calculate the point of impact, taking into account, for example, the relative sliding direction of the vehicle's movement to the stationary obstacle. This can also be done for directions of movement altered by support measures. Once the points of impact are known, the corresponding passive safety systems, such as airbags, and / or other relevant vehicle systems can be prepared for the collision.

[0034] These support measures advantageously provide for the cyclical reassessment of the driving situation relative to the environment, for example, whenever new radar data is available. This also occurs, in particular, after the detection of a skid, if radar data is taken into account for the support measure, as described above. Specifically, various support measures are conceivable within the scope of the present invention. For example, fully automatic stabilization of the vehicle can be implemented, whereby driving interventions can include not only lateral control interventions, which can be made at the steering system and / or the wheels, but also braking interventions and / or transmission interventions. Preferably, not only the dynamic parameters of the vehicle play a role, but also the nature of the environment (free space, stationary obstacles, large obstacles such as walls / guardrails / etc.).and / or small obstacles such as trees / traffic signs / etc.) are taken into account, at least partially using radar data. Semi-automatic assistance is also possible, whereby, for example, longitudinal driving interventions and / or interventions in the transmission are carried out automatically, but steering remains with the driver. The driver is preferably shown or advised a stabilizing driving direction, which is determined in particular based on environmental data. Finally, it is of course also conceivable to implement the assistance entirely through driving recommendations to the driver.

[0035] In addition to the method, the present invention also relates to a motor vehicle comprising at least one radar sensor and a driver assistance system for supporting the driver of the motor vehicle during a skidding process, wherein the driver assistance system includes a control unit configured to carry out the method according to the invention. All aspects relating to the method according to the invention can also be applied analogously to the motor vehicle according to the invention, with which the same advantages can therefore be obtained.

[0036] Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawing. The drawings show: Fig. 1 a schematic diagram of a motor vehicle according to the invention, Fig. 2 one in a motor vehicle according to Fig. 1 radar sensor used, Fig. 3 the motor vehicle while traveling along a road, Fig. 4. An illustration to explain a spin cycle, Fig. 5 an illustration of support measures during a spin cycle, and Fig. 6 An illustration of support measures for collision reduction.

[0037] Fig. Figure 1 shows a schematic diagram of a motor vehicle 1 according to the invention. This vehicle has eight radar sensors 2, three of which are concealed in the rear bumper, three in the front bumper and two in the doors of the motor vehicle 1.

[0038] Since these are wide-angle radar sensors 2 with an opening angle of the detection range 3 in azimuth of 150°, it is possible, as indicated by the detection ranges 3, to detect the surroundings of the motor vehicle 1 in a 360° radius.

[0039] Fig. Figure 2 shows the structure of the radar sensors 2 used in more detail. Each radar sensor 2 is implemented using semiconductor technology, specifically CMOS technology, and operates in a frequency band of 77 to 81 GHz with a frequency bandwidth of 4 GHz to deliver high-resolution radar data. The radar sensor has a housing 4 in which a circuit board 5 is mounted, which carries a package 6 consisting of a semiconductor chip 7 and an antenna assembly 8 of the radar sensor 2. The semiconductor chip 7, here a CMOS chip, integrates a radar transceiver 9, a control unit 10 of the radar sensor 2, and a digital signal processing component 11 (DSP) of the radar sensor 2.

[0040] When radar sensors 2 are activated, the radar data from radar sensors 2 are used, see below. Fig. 1, supplied to a central control unit 12 of the motor vehicle 1, which is also configured to carry out the method according to the invention, and is thus assigned to a driver assistance system 13 for supporting a driver during a skidding process of the motor vehicle. The control unit 12 therefore detects and classifies at least static objects from the radar data, and furthermore uses their relative movement to the motor vehicle 1 to detect a skidding process by means of at least one skidding criterion and, if the skidding criterion is met, to take support measures which may be directed at least partially towards automatically returning the motor vehicle to a stable driving state and / or at least partially towards issuing support instructions to the driver.The control unit 12 also evaluates certain dynamic parameters describing the driving dynamics of the vehicle 1 itself, for example, the vehicle's speed determined by measurements at the wheels, and the like. Corresponding measuring devices are located in . Fig. 1 simplified with reference numeral 14. The control unit 12 also communicates with a safety system 15 for collision mitigation or additionally implements such a system, so that if a collision criterion indicating an unavoidable collision is also met during a skidding process, the support measures can be aimed at collision mitigation.

[0041] Fig. Figure 3 shows the vehicle 1 in a driving situation on a road 16 that does not correspond to a skidding process. The radar sensors 2 make it possible to detect various static objects at the edge of the road 16, which also indicate the course of the roadway. Examples shown here include a curb 17, a guardrail 18, a roadside structure 19, a tree 20, and a sign 21. The high-resolution radar sensors 2, based on CMOS technology, also allow the transition 22 from the road surface to another surface to be detected as a boundary of the road 16, or its lane, even without a curb 17. During normal driving of the vehicle 1, these static objects can easily be recognized as being positioned in the world coordinate system, a fact further confirmed by time integration.

[0042] Fig. Figure 4 shows various positions 23, 24, and 25 of the vehicle 1 on the road 16 during a skid, and also shows three static objects 26 and 27 as examples. Although the direction of travel 28, as determined by the vehicle itself as a dynamic parameter based on the driver's inputs and settings, should run in the direction of the vehicle 1's longitudinal axis, an actual movement component 29 transverse to this direction apparently exists. This unintended movement 29 can be detected by the relative dynamics of the vehicle 1 with respect to the static objects 26 and 27, as measured by the radar sensors 2. This is because, viewed in the vehicle's coordinate system, the movement of the vehicle 1 is represented as the relative movement of the actually stationary static objects 26 and 27, which were also detected as such.

[0043] In a specific training scenario, a skid criterion can thus compare certain dynamic parameters within the vehicle itself with corresponding motion parameters of the dynamics of the static objects 26, 27, preferably for several static objects 26, 27. For example, if one compares the speed of the vehicle 1, as erroneously determined by the vehicle itself due to a lack of traction of the wheels, with the measured relative speed of the static objects 26, 27, a deviation in the skid state can be observed. A similar principle applies when... Fig. Figure 4 shows that this also applies to the direction of travel, because the motor vehicle is clearly not moving in the expected direction of travel relative to the static objects 26, 27. Such a comparison can also constitute a skidding criterion and / or be included in a skidding criterion.

[0044] Preferably, in this embodiment, the motion patterns of the static objects 26 resulting in the vehicle coordinate system are also compared or correlated with reference patterns in at least one skid criterion. These reference patterns describe typical temporal profiles or relationships between different temporal profiles during skid processes. A preselection of possible reference patterns, and thus possible skid processes, can be made based on the current vehicle dynamics parameters of the vehicle 1, particularly before the start of the skid process. The reference patterns are therefore preferably stored in a database in the control unit 12 and can be preselected and / or adjusted based on the vehicle dynamics parameters to simplify the comparison with the motion patterns actually measured from the radar data.Advantageously, because a comparison with a specific reference pattern is successful, the spin-off process is classified as corresponding to that specific reference pattern as early as the initial identification stage. This information is then taken into account when determining the specific support measures. For this purpose, support data sets containing support patterns are assigned to the reference patterns. These support patterns ultimately contain stabilization measures, such as countermeasures, tailored to the spin-off process.

[0045] However, when selecting or adapting support measures, the static objects 26, 27 and dynamic objects in the vicinity of the vehicle 1, detected from the radar data, are also taken into account in order to choose a stabilization strategy that does not itself lead to a critical situation. Thus, the selection of the optimal support measure also involves optimization with regard to a criticality value that describes the criticality of the resulting driving situation. For example, if a simple, immediate counter-steering maneuver in the direction originally intended by the driver would lead to a collision with a static object 26, 27 or a dynamic object, an alternative stabilization strategy can be chosen, for example, by a later counter-steering point, a different steering behavior, and / or a different stabilizing direction of travel.

[0046] Positions 30 to 32 of motor vehicle 1 during a successful stabilization procedure are by Fig. 5 indicated. There, through automatic driving interventions, which may also include interventions on individual wheels and / or an adjustment of the front axle to the rear axle, generally speaking, through lateral guidance, longitudinal guidance and parameterization interventions, the unwanted movement component 29 is transferred back into the driving direction 28 of the motor vehicle 1 as intended according to the settings, which is visibly achieved in position 32, as indicated by arrow 33.

[0047] However, stabilization without a collision is not always possible. Therefore, when a spin-out is detected, a collision criterion is also used to check whether an unavoidable collision with a static object 26 or a dynamic object could occur. In the example of the Fig.Figure 6, which shows further exemplary positions 34, 35, and 36 of the vehicle 1, shows that a collision with the static object 27 is unavoidable. In this case, the support measures serve not only to stabilize the vehicle 28, which is still the objective, as shown by the motion component 29, but also to minimize the severity of the collision. Therefore, in the present example, the impact area 37 of the vehicle 1 on the static object 27 is adjusted to minimize damage, and simultaneously, a corresponding reconditioning of the passive safety systems, in particular the airbag, of the vehicle 1 takes place, taking into account the predicted impact point 37. Thus, even in the event of an unavoidable collision due to a skidding process, ideal support for the driver is provided.

[0048] It should be noted that when considering environmental data, not only the static and dynamic objects detected by radar sensors 2 must be taken into account, but it is also conceivable to include further environmental data, such as camera data. Furthermore, it should be noted that instead of automatic stabilization / collision mitigation, semi-automatic vehicle control with corresponding support instructions for the unsupported control modes, particularly steering, is also conceivable; furthermore, the driver can be guided solely by support instructions.

Claims

[1] Method for operating a driver assistance system (13) for assisting a driver of a motor vehicle (1) during a skidding event, wherein, upon fulfillment of at least one of at least one skidding criterion indicating a skidding event, at least one support measure issuing a support instruction to the driver and / or comprising a driving intervention is carried out, characterized bythat radar data describing the surroundings of the motor vehicle (1) are recorded by means of at least one radar sensor (2) of the motor vehicle (1) and evaluated with regard to static objects (26, 27), wherein in order to detect a skidding process by means of the skidding criterion, the dynamics of at least one static object (26, 27) relative to the motor vehicle (1) are evaluated in their temporal course, wherein at least one of the at least one skidding criterion comprises a comparison of a movement pattern of at least one static reference object with regard to the motor vehicle (1) with at least one reference pattern describing a skidding state. [2] Method according to claim 1, characterized by that a radar sensor (2) with a semiconductor chip (7), in particular a CMOS chip, realizing at least one radar transceiver (9) is used as the radar sensor (2). [3] Method according to claim 2, characterized bythat a digital signal processing component (11) of the radar sensor (2) and / or a control unit (10) of the radar sensor (2) are additionally realized by the semiconductor chip (7) and / or the semiconductor chip (7) and an antenna arrangement (8) of the radar sensor (2) are realized as a package (6). [4] Method according to one of the preceding claims, characterized by that the radar sensor (2) is operated with a frequency bandwidth of at least 2 GHz, in particular at least 4 GHz, and / or in a frequency range of 77 to 81 GHz and / or several radar sensors (2) covering the surroundings of the motor vehicle (1) in a 360° radius are used. [5] Method according to one of the preceding claims, characterized bythat several static objects (26, 27) are evaluated within a skidding criterion and / or different skidding criteria and / or static objects (26, 27) describing the course of the roadway of a road (16) traveled by the motor vehicle (1) are used. [6] Method according to one of the preceding claims, characterized by that at least one of the at least one skidding criterion compares a dynamic parameter of the motor vehicle (1), in particular its speed and / or direction of travel, determined by measurement on the motor vehicle (1), with a corresponding movement parameter of the dynamics of the at least one static object (26, 27). [7] Method according to one of the preceding claims, characterized by that at least one edge development object (19) and / or an object (26, 27) indicating a lane boundary of a road (16) traveled by the motor vehicle (1) is used as a reference object. [8] Method according to one of the preceding claims, characterized by that the at least one reference pattern to be used for the comparison is selected from a database of reference patterns as a function of at least one dynamic parameter of the motor vehicle (1) determined by measurement on the motor vehicle (1) and / or scaled by this. [9] Method according to one of the preceding claims, characterized by that in the case of a spin process detected by successful comparison with a specific one of the at least one reference pattern, the support measure is selected and / or adapted depending on the specific reference pattern. [10] Method according to claim 9, characterized by that support data sets containing support patterns in particular are assigned to the reference patterns, wherein a support measure based on the support data set assigned to the specific reference pattern is carried out. [11] Method according to one of the preceding claims, characterized by that the support measure is determined and / or adapted as a function of the radar data, in particular of static and dynamic objects (26, 27) determined in the radar data. [12] Method according to one of the preceding claims, characterized by that, taking into account the radar data, if at least one of the at least one skidding criterion is fulfilled, a collision criterion indicating an unavoidable collision is checked, wherein, if the collision criterion is fulfilled, the support measures for mitigating the consequences of the collision are carried out. [13] Motor vehicle (1), comprising at least one radar sensor (2) and a driver assistance system (13) for assisting a driver of the motor vehicle (1) during a skidding process with a control unit (12) designed to carry out a method according to one of the preceding claims.

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